A zfs snapshot is a read-only copy of a Solaris ZFS file system or volume. Snapshots can be created almost instantly and initially consume no additional disk space within the pool. All normal users on Triton have access to their ZFS hidden file system at

$HOME/.zfs/

ZFS supports the ability to restore lost files with the standard UNIX copy command. See the example below.

• Triton's process for creating user accounts automatically creates both a ZFS (home) file system and a Lustre PFS account for each user.
• There are approximately 36 terabytes of storage in the home file system, to be shared by all users.
• Snapshots are taken nightly and then replicated. This ensures local data areas have both readily accessible backups and duplicates in case of failures to the home system.
• Triton currently retains snapshot archives for approximately 30 days. This policy will continue as long as the pool retains sufficient space for daily needs of the community.
• Users are requested to share the space responsibly, and to remove data in a timely fashion so the space becomes available for others.
• Users are expected to make their own permanent backups of valuable data on the home file system. ZFS Snapshots are NOT permanent backups. Further, the length of time for which snapshots are retained is subject to change without prior notice.

Example of ZFS Data Snapshot Restore Session

[juser@login-4-0 ~]$ ls
1G  4G
[juser@login-4-0 ~]$ ls .zfs
snapshot/
[juser@login-4-0 ~]$ ls .zfs/snapshot
SNAPSHOT2009-06-22-1245668520/  SNAPSHOT2009-06-24-1245841320/
SNAPSHOT2009-06-22-1245668674/  SNAPSHOT2009-06-25-1245927720/
SNAPSHOT2009-06-23-1245754920/  SNAPSHOT2009-06-26-1246014120/
[juser@login-4-0 ~]$ rm 1G
[juser@login-4-0 ~]$ ls
4G
[juser@login-4-0 ~]$ ls .zfs/snapshot/SNAPSHOT2009-06-26-1246014120/
1G  4G
[juser@login-4-0 ~]$ cp .zfs/snapshot/SNAPSHOT2009-06-26-1246014120/1G .
[juser@login-4-0 ~]$ ls
1G  4G
[juser@login-4-0 ~]$